1. Field of the Invention
This invention relates in general to tape head assemblies, and more particularly to a method and apparatus for providing tape head assemblies for very high density recording.
2. Description of Related Art
In high-speed data processing systems, magnetic recording has been employed for large storage capacity requirements. In magnetic storage systems, data is read from and written onto magnetic recording media utilizing magnetic transducers commonly referred to as magnetic heads. Data is written on the magnetic material by moving a magnetic recording head to a position over the magnetic material where the data is to be stored. The magnetic recording head then generates a magnetic field, which encodes the data into the magnetic material. Data is read from the media by similarly positioning the magnetic read head and then sensing the magnetic field of the magnetic material. Read and write operations are independently synchronized with the movement of the media to insure that the data can be read from and written to the desired location on the magnetic material.
An important and continuing goal in the data storage industry is that of increasing the density of data stored on a medium. For tape storage systems, that goal has lead to increasing the track density on recording tape, and decreasing the thickness of the magnetic tape medium. However, the development of small footprint, higher performance tape drive systems has created various problems in the design of a tape head assembly for use in such systems.
In a tape drive system, magnetic tape is moved over the tape surface of the tape head at high speed. This movement generally entrains a film of air between the head and tape. Usually the tape head is designed to minimize the spacing between the head and the tape.
During operation, an actuator mechanism moves the head and magnetic transducers to a desired position on the surface of the moving medium where the head electromagnetically reads or writes data. Typically, the magnetic transducers are integrally fabricated in a carrier or support referred to as a xe2x80x9csliderxe2x80x9d. The slider generally serves to mechanically support the head transducers and any electrical connections between the head and the remainder of the storage system.
In order to meet the demand for increasing areal densities in magnetic tape, many technological innovations are required. In order to improve data reliability, a read element corresponding to each write element reads the magnetic field from the tape immediately after it is written. This technique is known as read-while-write. To increase data transfer, the tape may be written as it travels in either direction across the tape head. This requires a read element downstream of each write resulting in a read-write-read head configuration.
A read-while-write head assembly comprises a write element in-line with a read element, the gap of the read element being accurately spaced to the gap of the write element, with the read element positioned downstream of the write element in the direction of tape motion. By continually reading xe2x80x9cjust recordedxe2x80x9d data, the quality of the recorded data is immediately determinable at a time when the original data is still available in temporary storage in the recording system. The reproduced data is checked against the original data, and appropriate action, such as re-recording, may be taken in case of error.
Conventional thin film tape heads are fabricated using processes similar to those used in direct access storage device (DASD)) heads. The process provides a plurality of layers deposited on the surface of a substrate to form the tape head transducers. For a tape head assembly, the read-after-write pair of magnetic recording heads include a first write element adjacent to a read element which is adjacent to a second write element, or a first read element adjacent to a write element which is adjacent to a second read element. Cables are then electrically attached to the heads to provide signal leads.
The next step is to join the cabled heads together to form the read-while-write unit. However, the two tape head sections may shift relative to one another during this joining process. Shifting of the two modules can affect tape wrap angle, track-to-track registration, and head-to-head parallelism. Previous two module tape head build methods do not have generally the required level of precision for modern high density recording applications.
In addition, heads are now built with flat rather than curved tape bearing surfaces, as described in U.S. Pat. No. 5,905,613. These heads, when constructed for high density recording, have critical module-to-module alignment
It can be seen that there is a need for a method and apparatus for providing tape head assemblies that prevent head shifting during adhesive setting.
It can be seen that there is a need for a method and apparatus for providing tape head assemblies that provides precise tape wrap angle setting, track-to-track registration, and head-to-head parallelism.
To overcome the limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention discloses a method and apparatus for providing tape head assemblies that prevent module misalignment during assembly.
The present invention solves the above-described problems by attaching a read-after-write pair of magnetic recording heads to two rigid, precision U-shaped support beams that are subsequently joined together by joining the legs of the U-shaped support beams using, for example, a joining agent. Distortions caused by the joining process have minimal effect on wrap angle and track-to-track registration. For example, if the joining agent expands or contracts during the assembly process, the dominant effect is to slightly alter the module-to-module separation, not the angle, relative height or track-to-track alignment.
A tape head sub-assembly in accordance with the principles of the present invention includes a support beam having engagement surfaces and a recessed area disposed between the engagement surfaces and a tape head disposed on the support beam, wherein the recess area provides a cable receptacle for framing a cable that is attached to the tape head.
Other embodiments of a tape head sub-assembly in accordance with the principles of the invention may include alternative or optional additional aspects. One such aspect of the tape head sub-assembly of the present invention is that the support beam further comprises an angled edge on the engagement surface to provide a predetermined tape wrap angle.
Another aspect of the tape head sub-assembly of the present invention is that the support beam further comprises an angled top surface on the engagement surface to provide a predetermined tape wrap angle.
Another aspect of the tape head sub-assembly of the present invention is that the tape head comprises a substrate and a closure piece separated by a plurality of layers forming magnetic transducers.
In another embodiment of the present invention, a tape head is provided. The tape head includes a matched support beam pair, each support beam having a tape head disposed on the support beam, each support beam further including engagement surfaces and a recessed area disposed between the engagement surfaces the matched pair being joined at the engagement surfaces, the recess areas providing a cable receptacle for framing a cable that is attached to the tape head.
Another aspect of the tape head of the present invention is that each of the support beams further includes an angled engagement surface to provide a predetermined tape wrap angle.
Another aspect of the tape head of the present invention is that each of the support beams further includes an angled top surface to provide a predetermined tape wrap angle.
Another aspect of the tape head of the present invention is that the angled front edge provides a tape wrap angle of approximately 1.2 to 2.0 degrees.
Another aspect of the tape head of the present invention is that each of the tape heads includes a substrate and a closure piece separated by a plurality of layers forming magnetic transducers.
Another aspect of the tape head of the present invention is that the engagement areas are aligned to provide critical height, wrap angle and track-to-track alignment.
Another aspect of the tape head of the present invention is that the tape head further includes a joining agent disposed between the engagement areas to join the two support beams together.
A further embodiment of the present invention provides yet another tape head. The tape head includes a pair of matched support means, each support means including a tape head disposed on the support beam, each support means further including engagement means and a cable receptacle means disposed between the engagement means for framing a cable that is attached to the tape head, the pair of matched support means being joined at the engagement means.
In another embodiment of the present invention, a method of forming a tape head is provided. The method for forming the tape head includes positioning a pair of support beams each having engagement areas and a recessed area with the engagement areas of a first of the pair of support beams in close proximity to the engagement areas of a second of the pair of support beams, performing a predetermined alignment of the pair of support beams and joining the pair of support beams together using a joining agent in a gap between the engagement areas of the support beams.
Another aspect of the method for forming a tape head according to the present invention is that the support beams further comprise a tape head bonded to a top surface of each support beam.
Another aspect of the method for forming a tape head according to the present invention is that the tape heads include wafer processed thin film tape heads.
Another aspect of the method for forming a tape head according to the present invention is that the method further includes coupling cables to the tape heads and to the support beams in the recessed areas to provide strain relief in the region between the engagement areas.
Another aspect of the method for forming a tape head according to the present invention is that the support beams are generally U-shaped.
Another aspect of the method for forming a tape head according to the present invention is that performing a predetermined alignment of the pair of support beams further includes performing height, wrap angle and track-to-track alignments.
These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and form a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to accompanying descriptive matter, in which there are illustrated and described specific examples of an apparatus in accordance with the invention.